If truth is the first casualty of war, in Washington's war on terror language proved another early victim. From "the axis of evil" to "enemy combatants", the warping of words prefigured the bending of legal and military logic. But no lexicographic concoction is quite as sinister as "extraordinary rendition". The practice can be more plainly described as kidnapping and torture. A powerful new film, screened on BBC1 tonight, explores the human consequences of the CIA's secret programme.

The film, Extraordinary Rendition, is fictional, starting with an abduction in London, where none has ever been reported. The premise, however, is that what is shown could happen. When abduction has occurred in the streets of Milan, and when EU countries have 39 outstanding arrest warrants for alleged CIA operatives, that seems feasible enough. Equally plausible is the harrowing portrayal of what happens next. After being flown - lawyerless and clueless - via a third country, the victim arrives in a Middle Eastern cell. He is subject to the brutalities deployed in real cases, including whipping and simulated drowning.

Vice-President Dick Cheney is one of those who has sometimes seemed to question whether this last practice, known as waterboarding, amounts to real torture. History's archetypal torturers had no such doubts: the Spanish inquisition used the same technique and called it tortura del agua. Earlier this month Washington released an official document from 2003 that gave the US military dubious authorisation to use harsh tactics against al-Qaida and the Taliban. The incident underlines again the Bush administration's contempt for international law and human rights. All three candidates for the presidency next year take issue with its approach, arguing that brutish interrogation produces unreliable information and serves as a recruiting sergeant for terrorists.

The British government has not always taken the same critical line. The security service passed information to the Americans on British residents who were later seized in Gambia. In February, after years of denials, the foreign secretary admitted that two CIA rendition flights had touched down in a British-controlled territory. He admitted to being "disappointed" to discover this, though he has still not publicly demanded the full details from the Americans. The allegations of MI5 collusion in Pakistani interrogation reported in yesterday's Guardian raise further uncomfortable questions.

London must reaffirm that the ban on torture is an absolute. It must insist that no ally, however powerful, will be assisted in trying to find workarounds. Human rights cannot be wished away by outsourcing or rebranding.